A concentric cylindrical rheometer has been designed to investigate the rheological properties of high polymer liquids under high static pressure. One can employ this apparatus either as a Couette-type viscometer or as a torsionally oscillating rheometer to measure the steady shear viscosity or the dynamic viscoelasticity, respectively. When the outer cup is forced to rotate or oscillate, the displacement of the inner bob is detected by making use of the change in the electric resistances of the wire strain gauges fastened to the surface of the torsional plate. Compressed nitrogen gas is used as the pressure medium and the pressure ranges from 0 to 2000 kg/cm² (in gauge). The maximum temperature is limited to 170°C because of the temperature limit of the strain gauge. A correction is required for the pressure dependence of the apparent sensitivity of the strain gauge.
Preliminary measurement was made with reasonable results.

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By means of a concentric cylindrical rheometer for high pressure, the viscosity was measured for polydimethylsiloxane melts with various weight average molecular weights under static pressure up to 900 kg/cm² at 25°C. This study aimed to discuss the effect of pressure on the molecular weight dependence of zero shear viscosity and on the critical molecular weight, Mc, related to the build-up of the entanglement between polymer chains.
(1)η_p, increases with static pressure in all cases.
η_p/η₀ is almost independent of M_w; M_w<1×10⁴ and M_w> 8×10⁴,
where s and s are the zero shear viscosities under static pressure P and atmospheric pressure, respectively, and K, n and A are independent of P and M_w.
(2) The so-called 3.4 power law is valid under each pressure.
(3) M_c is slightly dependent on static pressure.

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Rheological properties were studied on melts of various conventional high density polyethylenes and their fractions using a cone plate and a capillary type rheometers. Shapes of viscosity master curves depend on the molecular weight distribution but not the molecular weight. Non-Newtonian property increases with the broadness of the molecular weight distribution.
Normal stress in a parallel plate rheogoniometer was measured rapidly with an electronic device. Relationship between the shear stress and the normal stress depends on the molecular weight distribution but not the molecular weight and that the apparent compliance and the recoverable shear strain of broad molecular weight distribution polymers are larger than those of narrow distribution polymers.

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Effects of molecular weight and molecular weight distribution on the entrance pressure drop, the end correction factor, the Barus effect, and the melt fracture have been studied for commercial high density polyethylenes and their fractions. The measurements were made with a Koka flow tester at 190°C.
The end correction factors of the fractions were nearly equal to the Couette constant. These factors and the entrance pressure drop increared with the broadness of the molecular weight distribution. A correlation was found between the entrance pressure drop and the normal stress, but the absolute value of the former did not agree with that of the latter.
The Barus effect also increased with the broadness of the molecular weight distribution.
The melt fracture of the fractions occured in the range of shear stress, 2-4×10⁶ dyne/cm², irrespective of the molecular weight. The lower critical shear rate, γ_CL at which the melt fracture begins, decreased with the molecularweight. For two component blended samples, γ_CL, increased with the molecular weight distribution, M_zM_w.

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Stress relaxation curves were obtained for ionomers containing different cations and percents of ionization. Based polymer used here was a copolymer of styrene methacrylic acid (85/15). The rate of stress relaxation was in the order of Na⁺-ionomer, based polymer and Zn⁺⁺-ionomer. The stress relaxation behavior of these/polymers showed as if they were crystalline polymers. A recently proposed model for ionomers is discussed and found to be consistent with these results. By application of W. L. F. equation for these polymers, it was found that there were two different terms of stress relaxation mechanism among the polymer molecules. The primary and secondary transitions observed in solid polymers have generally been interpreted in terms of concept of “molecular motions”. On the other hand, R. D. Andrews has proposedthat these transition are explained in terms of thethermal breakdown of different types of intermolecular secondary bonding in the solid state. Stress relaxation mechanism in this study was well explained by R. D. Andrews definition for polymer transition.

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Elastic behavior of composite materials whose components are firmly bonded together were analyzed in terms of strain energy. The inhomogeneity effect, which was introduced as the measure of the interfacial interaction of each component, on the apparent Young's moduli was studied.
Arbitrary composite model was devided into many right prism elements, and the inhomogeneity effect energy for the model was derived approximately by the series or parallel combination of the elements. Approximate analytical equations representing the inhomogeneity effect and the apparent Young's moduli of the series and parallel models were derived.

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Mechanical properties of two-component systems whose components are firmly bonded together were analyzed by the computer simulation using finite element method. The results agreed well with those calculated by use of approximate analytical equations for two-component unit models reported in the preceding paper.

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Effect of holding pressure on the pressure behaviors of HDPE in the mold cavity during injection molding is studied. The resin pressure at the nozzle during the holding time is not always the same as the holding pressure shown in the pressure gauge mounted in the hydraulic oil circuit and strongly depends on the quantity of resin remaining at the front of the screw head in the heating cylinder (cushion volume) after completion of the injection.
The holding pressure has two roles; one is to supply the same quantity of the resin in the mold cavity as contracted by cooling. The other is to prevent the back flow of the resin during the holding time. With increasing holding pressures the article weight increases due to the increase of static pressure and the prolongation of pressure remaining time of the resin in the cavity. Under the same holding pressure, the increase of cylinder and mold temperatures leads same results, because the pressure loss from the nozzle to the gate is reduced.
The gate seal time and the stop time of flow of melt during the holding time can be estimated from the pressure profile at 20 and 70 mm from the gate.

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Mold shrinkages of injection molded articles of HDPE depend remarkably on the pressure behaviors of the resin in the mold cavity, the molding procedures and the molding conditions. Effects of the cushion volume, the initial filling volume, the screw forward time and the holding pressure on the mold shrinkages were examined. In these cases cushion was used to keep the holding pressure constant during the holding time.
The holding pressure has large effects on the mold shrinkage and the static pressure in the pressure profile in the mold cavity. With increasing holding pressure the mold shrinkages in parallel and perpendicular directions to the flow of melt decrease and the anisotropy of the mold shrinkage increases.
Solidification time of the melt determined from the mold shrinkage and the pressure remaining time are prolonged with the increase of cylinder temperature and mold temperature. This solidification time agrees fairly well with calculated values. It seems that flow orientation which brings anisotropy of mold shrinkage is markedly governed by the resin temperature and the driving force during the filling process.

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Change of physical properties of high density polyethylene by heat and mechanical treatment has been studied with High Speed Twin Screw Mixer (Type CIM-120).
The treated samples had narrow molecular weight distribution and high melt index. This may be due to the reduction of high molecular weight fraction compared with original samples.
Futhermore, the melt index of the treated samples was lower than that of untreated ones having the same reduced viscosity, η_sp/C.η_sp/C of the treated samples was smaller than that of the original system having the same number average molecular weight.
The values of the activation energy of the treated samples above thc melt temperature lie between that of low density and high density polyethylene.
Above results suggest that the change in the physical properties by the treatment may be due to a prefferential scission of bonds of the high molecular fraction and the formation of long chain branching.

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The relations between melt index and operating factors of processing machines of different type were investigated for the purpose of controlling molecular weight and its distribution of polypropylene having low melt indices. by using industrial plastic processing equipments. The conventional type extruders had the functions to control melt index under severe operating conditions, especially high-speed type twin extruder had the most effective functions.

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The authors et al. made some experiments on injection-molded records in order to find out the best material for them and the best injection condition.
Vinyl chloride-vinyl acetate copolymer, polymethyl methacrylate and modified polystyrene were used in these experiments, and their fluidity measured.
Weir's α STV was adopted as moldability parameter so as to compare the molding processability of each material. It was concluded that vinyl chloride-vinyl acetate copolymer is the best for making disk records by injectionmolding. An investigation was made on thc influence which mold temperature and clamping force have on moldability of disk record, intermodulation distortion, and signal-to-noise ratio. It was certified that vinyl chloride-vinyl acetate copolymer has a smaller α STV value than any other material at optimum molding temperature. This means vinyl chloride-vinyl acetate is hard to mold and also that it has a better acoustical characteristic of wear resistance and signal-to-noise ratio etc, on disk records than any other material.
Besides, the authors et al. measured the influence of moldability of records against various injection conditions, varying the bottom and edge minimum radius of the tone groove. Finally, it was found that mold temperature influenced moldability of records and signal-to-noise ratio greatly, and that a temperature of at least 40°C and cl amping force of more than 100 tons are therefore required.

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Molecular orientation in injection-molded disk records influences the mechanical strength and signal-to-noise ratio. We considered mold temperature, clamping force, rate of injection, injection pressure, and polymer temperature to be among injection-molding conditions for making records by vinyl chloride-vinyl acetate copolymer. Then, we investigated the relation between measurement data and orientation degree by means of 7-inch records which were produced under each injection-molding condition. With regard to measurement items, we measured impact strength, tensile strength, signal-to-noise ratio, intermodulation distortion and of course orientation degreeor all the records produced under the aforementioned conditions.
The degree of molecular orientation of an injection-molded record is always less than 0.1.
The degree under normal injection-molding conditions of records is about 0.02 to 0.04 which is comparatively low.
Furthermore, we found that the orientation degree was influenced by injection pressure and polymer temperature greatly; it decreased abruptly when polymer temperature reached more than 185°C, and increased in proportion to increment of injection pressure.
Besides, signal-to-noise ratio deteriorated in inverse proportion to increment of the orientation degree, though it was within I to 2 dB in the range of injection-molding conditions of the disk records.

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To solve the fundamental problems for volume change and internal stress during cure, the volume change, the glass transition temperature, the expansion coefficient and the young's modulus were measured during cure.
These value changed according to the 1st. order reaction.
The following experimental equation is found:
Were:β: ratio of volume shrinkage at curing and cooling.β₁: volume shrinkage with chemical reaction for cured resin.β₂: T_q. of cured resin. k: reaction velocity.β0 expansion coefficient of liq. epoxy resin.β'; expansion coefficient below T_q.β∞: expansion coefficient above T_q. C₁: curing temperature. C₂: room temperature (arbitrary temperature bellow T_q). t: reaction time.

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Workmanship of the hand lay up method of GRP was investigated in order to establish the evaluation standard.
From comparison between flat panels made by skilled (A₁) and unskilled (A₂) workman by the measurements of tensile and flexural properties, it was pointed out that the workmanship should be classified not by these properties but by the deviation of the thickness from the designated value, the standard deviation of thickness, the glass content, the void content and the mechanical properties.
The workmanship was also studied for the molding at 15, 23 and 30°C. Deviation of the thickness from designated value for A₂ were larger than that for A₁, and the standard deviation for A, were larger than that for A₁.
The flow of GRP during molding at higher temperature was greater than that at lower temperature.
Four kinds of curing condition, e. g., room temperature curing, immersion in water and heat curing, were compared by the mechanical properties.

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Deep drawing of six types of vinyl polymers and copolymers were tested using the newly developed apparatus constructed in Instron Universal Testing Instrument.
Effects of temperature and speed on the drawability of materials have been discussed, and the following results were obtained. 1) The optimum temperature of deep drawing is in the range of the glass transition temperature (T_g1<T_g2) observed by thermal analysis. 2) Phenomena of whitening at the bottom of a cup are apt to diminish above T_g1 Vinyl chloride-propylene copolymer shows the minimum whitening among six materials. 3) The dimensions of cup measured immediately after being drawn became larger than the outside diameter of the punch, when a cup is made above T_g2. 4) Maximum punch force decreases with increasing temperature, and it decreases remarkably above T_g1. 5) Maximum punch force does not change with punch speed.

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Using newly designed drilling test equipment, drilling of multi-layer printed-circuit board were studied. Requirements for the inner surface of drilled holes are so severe that special apparatus for observation of the hole were developed. Optimum shapes of drill were decided by the observation of holes under the various drilling conditions. Materials used here are the composite of epoxy-resin and glass-cloth, so economics of drilling depend mainly on the wear of drill, the effects of drilling conditions on the drill wear were studied. On the viewpoint of characteristics of hole and drill wear, optimum drilling conditions were obtained.

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When nylon 6 monofilament is made by water quenching in the process of melt spinning, a skin and core structure is usually observed in its cross section. By the method of micro infrared spectroscopy, it was found that the skin was composed of γ-form crystal structure, whereas the core possesses less ordered quasi-hexagonal crystal structure. Under the polarized and electron microscope, many sphcrulites were observed in the skin structure.
It was surmised that the water permeated from the surface into the core of the monofilament accelerated to a great extent the crystallization rate of nylon 6 spun into the cooling water bath. This was confirmed by investigating the crystal structure and the growth rate of spherulites bulk crystallized from the molten nylon 6 containing various amount of water. An experiment of crystallization under pressure in an autoclave was carried out for this purpose.

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The structural changes of poly (vinylalcohol)(PVA) films as a result of thermal-oxidative treatment at 230°C for various times were investigated by infrared spectroscopy, X-ray diffraction, and dynamic viscoelasticity. With the thermal-oxidation, the crystalline portions of the samples decreased with increasing treatment time and finally disappeared.
For these amorphous PVA films obtained by the thermal-oxidation, the tanδ peak corresponding to the primary dispersion (ð_a) at about 70°C and the crystalline dispersion (β_c) at about 130°C almost disappeared and a new tanδ peak (δ_a) was observed at about 95°C. These results show that the segmental motion in the amorphous PVA films resulting from the thermal-oxidation was fairly simple in spite of involving many kinds of structures, such as carbonyl compounds, polyene and low molecular weight fractions.

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Interactions between polystyrene and fillers having common benzyl group, e.g., styrene-grafted cellulose and partially benzylated cellulose, have been studied and the results were compared with those of cellulose filler.
To this end the rheological characteristics of the melt in capillary flow and the mechanical properties of the molded sheet were determined with the following results.
1) The melt containing filler showed higher plastic viscosity and lower Barus effect with increasing content of styrene-grafted cellulose, as in the case of cellulose, but it was scarecely affected by the partially benzylated cellulose.
2) Filling with the partially benzylated cellulose improved the mechanical properties of the general purpose polystyrene sheet.
3) The filler covered with many short benzyl groups seems to be more effective to polystyrene than that grafted with a few long polystyrene chains.grafted with a few long polystyrene chains.

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The fracture mechanism of plane bending fatigue of polyvinyl chloride specimen prepared by different mold methods is studied from the stand point of fractgraphy. Two kinds of the specimens followed Paris's formula for the relation between the crack growth rates and the crack tip stress intensity factors. The striations were observed on the fracture surfaces of the specimens prepared by certain mold method. The number of these striations were less than that of the repetitions of tensile load. For the specimens made by other method, a main crack grew from the sub cracks without striations on the fracture surfaces.

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The effects of plasticizer and blended ABS resin on the crack propagation of polyvinyl chloride specimen under the repeated tensile stress at low cycle were investigated.
The fatigue life of the specimen without plasticizer was longer than that of the plasticized specimen and was shorter than that of the specimen with ABS resin. All of the specimens followed Paris's formula for the relation between the crack growth rates and the crack tip stress intensity factors. No striations were observed on every fracture suriace of the molded specimens but dimple patterns were observed on these surfaces. Many voids were found on the fracture surfaces of the specimens containing plasticizer. The fracture surface of the specimen without ABS resin was more rough than that of the specimen with it.

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Statistically designed experiments were carried out to study effects of molding condition, molecular orientation, and molecular weight on the Izod impact strength of the injection molded polycarbonate at room temperature and -25°C. The ductile strength at room temperature was not affected by the molding condition and molecular orientation, but it was strongly affected by the molecular weight, e.g., the maximum value was 97.8 kg. cm/cm at the molecular weight of 3.2×10⁴. The higher the mold temperature, or the lower the molecular weight, the higher the percentage of brittle break at -25°C. At low temperature, the specimen under the Izod impact was most brittle in the parallel direction to the molecular orientation, and in the perpendicular direction, the higher the molecular orientation the more brittle the specimen.

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Brittle fracture of low density polyethylene at low temperature was studied by means of uniaxial tensile test, impact brittleness test, and biaxial stress test.
Stress concentration, caused by the presence of notch or by the partial fracture of a composite structure, greatly affects the brittleness temperature of low density polyethylene, and stress polyaxiality also affects the brittleness temperature, e.g., low density polyethylene is more brittle under biaxial stress than under uniaxial stress. Effect of other factors was also investigated. The lower the melt index or the density of the polymer was, the lower the brittleness temperature. Chemical modification of the polymer chain, such as crosslinking or copolymerization, improved the low temperature flexibility of the polymer.

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